From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1161440AbWFVXRi (ORCPT ); Thu, 22 Jun 2006 19:17:38 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1030470AbWFVXRi (ORCPT ); Thu, 22 Jun 2006 19:17:38 -0400 Received: from mail.tv-sign.ru ([213.234.233.51]:7616 "EHLO several.ru") by vger.kernel.org with ESMTP id S1030466AbWFVXRh (ORCPT ); Thu, 22 Jun 2006 19:17:37 -0400 Date: Fri, 23 Jun 2006 07:17:39 +0400 From: Oleg Nesterov To: Ingo Molnar Cc: Andrew Morton , linux-kernel@vger.kernel.org Subject: [PATCH 2/2] sched_exit: move the callsite to do_exit() Message-ID: <20060623031739.GA2793@oleg> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.11 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org sched_exit() is called by release_task(). If the task auto-reaps itself this call happens a bit too early (the task still uses cpu after that). If the task goes to TASK_ZOMBIE this call is unpredictably delayed. I think it is better to do sched_exit() right before the last schedule(). We can use read_lock_rcu() instead of write_lock(tasklist). In that case it is possible that sched_exit() changes ->time_slice/->sleep_avg of the already dead ->parent, but I think this is tolerable. Signed-off-by: Oleg Nesterov --- 2.6.17-rc6/kernel/sched.c~MOVE 2006-06-23 04:48:48.000000000 +0400 +++ 2.6.17-rc6/kernel/sched.c 2006-06-23 06:46:57.000000000 +0400 @@ -1479,10 +1479,13 @@ void fastcall wake_up_new_task(task_t *p */ void fastcall sched_exit(task_t *p) { - task_t *parent = p->parent; + task_t *parent; unsigned long flags; runqueue_t *rq; + rcu_read_lock(); + parent = p->real_parent; + /* * If the child was a (relative-) CPU hog then decrease * the sleep_avg of the parent as well. @@ -1498,6 +1501,7 @@ void fastcall sched_exit(task_t *p) (EXIT_WEIGHT + 1) * EXIT_WEIGHT + p->sleep_avg / (EXIT_WEIGHT + 1); task_rq_unlock(rq, &flags); + rcu_read_unlock(); } /** --- 2.6.17-rc6/kernel/exit.c~MOVE 2006-06-18 06:10:26.000000000 +0400 +++ 2.6.17-rc6/kernel/exit.c 2006-06-23 05:45:42.000000000 +0400 @@ -170,7 +170,6 @@ repeat: zap_leader = (leader->exit_signal == -1); } - sched_exit(p); write_unlock_irq(&tasklist_lock); spin_unlock(&p->proc_lock); proc_pid_flush(proc_dentry); @@ -940,6 +939,8 @@ fastcall NORET_TYPE void do_exit(long co if (tsk->splice_pipe) __free_pipe_info(tsk->splice_pipe); + sched_exit(tsk); + /* PF_DEAD causes final put_task_struct after we schedule. */ preempt_disable(); BUG_ON(tsk->flags & PF_DEAD);